<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta
	content="width=device-width,initial-scale=1.0,maximum-scale=1.0,user-scalable=no"
	id="viewport" name="viewport">
<title></title>
<script src="http://libs.baidu.com/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript">  
	var countdown=60;  
	function settime(obj) {  
		if (countdown == 0) {
			obj.removeAttribute("disabled");  
			obj.value="免费获取验证码";  
			countdown = 60;  
			return;
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			obj.setAttribute("disabled", true);  
			obj.value="重新发送(" + countdown + ")";  
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		}  
		setTimeout(function(){ 
		settime(obj)} ,1000)
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</script>
<body>
	<input type="button" id="btn" value="免费获取验证码" onclick="settime(this)" />
</body>
</html>